Multi-end knit-deknit process

ABSTRACT

An improvement in a knit-deknit process wherein a plurality of yarns are angularly converged to a single bundle which is knit into tubing and heat-set. The tube is maintained in a twistless state while being unraveled and the unraveled bundle is separated and taken up as separate yarns.

United States Patent 1 Roberson, Jr.

MULTI-END KNIT-DEKNIT PROCESS Elbert Belmont Roberson, Jr., Wilmington, Del.

Inventor:

Assignee: E. I. du Pont de Nemours and Company, Wilmington, Del.

Filed: Jan. 6, 1971 App1.No.: 104,219

US. Cl ..28/72.l6, 66/132 R, 66/136 Int. Cl. ..D04b 19/00 Field of Search ..28/72.16; 66/136 References Cited UNITED STATES PATENTS 2/1909 Hirner ..66/136 4/1912 Hirner ..66/136 lMarch 20, 1973 3,321,818 5/1967 Scruggs ..28/72.l6 UX 3,333,441 8/1967 Soussloif et a1 ..28/72.16 X 3,568,277 3/1971 Mattingly ..28/72. 16

FOREIGN PATENTS OR APPLICATIONS 1,453,387 8/1966 France ..28/72.16

Primary Examiner-Robert R. Mackey Attorney-Howard P. West, Jr.

[ 5 7 ABSTRACT An improvement in a knit-deknit process wherein a plurality of yarns are angularly converged to a single bundle which is knit into tubing and heat-set. The tube is maintained in a twistless state while being unraveled and the unraveled bundle is separated and taken up as separate yarns.

3 Claims, 8 Drawing Figures PATENTEDMAREO ma 3. 720.984 SHEEI 2 BF 2 INVENTOR ELBERT BELMONT ROBERSON, JR

ATTORNEY MULTI-END KNlT-DEKNIT PROCESS BACKGROUND OF THE INVENTION This invention relates to the texturing of yarn by a process known as knit-deknit texturing. More particularly, the invention relates to a method for greatly increasing the productivity of such a process.

The knit-deknit process is well known and widely used. It is also known that in circular knitting, more than one yarn can be fed simultaneously to a single needle. In spite of the long history of circular knitting and knit-deknit processing, no process has been devised, as far as applicant is aware, which successfully utilizes the concept of circular-knitting a plurality of yarns combined as a single end, heat-setting the knit tubing, unraveling the combined single end, separating the unraveled end into the plurality of original yarns, and taking up the individual textured yarns separately. Previous attempts to accomplish this result have failed because twisting and tangling of the individual ends result quickly in yarn-breakage and consequent inoperability.

SUMMARY OF THE INVENTION This invention provides a process by which the productivity of a knitting head in knit-deknit texturing can be increased several fold. It further provides a process whereby a'plurality of yarns are knitted and deknitted together, being heat-set intermediately, and the plurality of textured yarns are taken up separately in a continuous operation.

The above provisions are accomplished by an improvement in a process for texturing yarn that includes the steps of knitting a single end of yarn into a tube without the introduction of real twist, heat-setting the tube, unraveling the yarn from the tube and winding the unraveled yarn-end into a package. The improvement comprises feeding a plurality of yarn-ends at substantially equal linear speeds from stationary sources along separate-yarn paths, converging the yarn-ends along differently angled paths with respect to each other into a bundle and knitting the bundle into a tube. After heat-setting, the bundle is unraveled from the tube and separated into individual yarn-ends each of which is taken up at about the same linear speed. During unraveling, the knit tube is maintained in a twistless state, i.e., it is collected andthen fed to the unraveling or deknitting operation without permitting the introduction of real twist. For this process to operate satisfactorily, provision is made for the relaxation of any false twist introduced by arranging for each feedyarn to converge at a different angle so false twist will be forcibly released by slippage at the point where the yarn-ends converge into a bundle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation in elevation of one manner of knitting and heat-setting according to this invention.

FIG. 2 is a preferred variation of the method of FIG. 1.

FIGS, 3 and 4 are topand side-view, respectively, of

'deknitting two ends of yarn according to this invention.

FIGS. 5 and 6 are analagous to FIGS. 3 and 4, showing deknitting of four ends of yarn.

FIG. 7 represents schematically a preferred embodiment of this invention wherein knitting and deknitting are coupled in a single continuous process.

FIG. 8 represents a partial elevation of the embodiment of FIG. 4 modified to include an additional tensioning arrangement.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS With reference to FIG. 1, a plurality of yarnpackages 12 (only two shown, for clarity) are provided on a stationary creel 42. Each individual yam-end 10 is led via guides 30 to a single convergence-guide 44 in close proximity to and centered above a circularknitting head 16. Knitting head 16 has a stationary circular bed (not shown) of knitting needles. By stationary", as applied to creel 42 and the needle-bed of knitting head 16, is meant that the respective devices are not only fixedly positioned in space but also nonrotating. A ring-like rotating feed-device 18, concen tric with the circular needle-bed, rotates about the vertical axis of the knitting machine. The converged bundle 14 of individual yarn-ends 10 passes from convergence-guide 44 to and through a. single opening 20 in rotating feed-device 18 whereby bundle 14 is fed as if it were a single yarn-end successively to the needles of knitting head 16. A knit-tubing 22 is continuously produced which does not rotate because it is formed on a stationary needle-bed. Tubing 22 is collapsed on passage through nip-rolls 24 to a two-layer flat fabric which is conveyed by cooperating; driven rolls 28. Intermediate to rolls 24 and 28, flattened tubing 22 is heat set by exposure to heat sufficient to relieve the forces of distortion due to knitting and to cause bundle 14 to retain subsequently these distortions, i.e., be textured. As shown, heat-setting is accomplished between two heated devices 26 contacting opposite faces of flattened tubing 22. Rolls 28 may be replaced by windup means for tubing 22, may forward tubing 22 to further processing, or may feed the tubing into intermediate packaging.

The variation shown in FIG. 2 is entirely analagous to the description above except between convergenceguide 44 and feed-opening 20 in rotating feed-device l8. Positive-feed yarn-metering devices are frequently employed in circular knitting. For example, device 32 is rotated in timed relation with the knitting speed. It comprises a series of pulleys with high-friction surfaces and stepped diameters. Regardless of which pulleythe bundle 14 engages, the rate of linear feedis positively controlled. The differing diameters of the pulleys provide for differing tensions at the knitting needles, control the tightness of knit stitches, and generally provide a control on quality of resultant yarn-texturing. In this variation, individual yarn-ends 10 converge at convergence-guide 44 positioned as near as practicable to positive-feed device 32. In FIG. 2, the yarn-path from guide 44 to device 32 is drawn at an angle for clarity; in practice it would be horizontal to prevent wandering of bundle 14 on device 32. Departing from device 32, yarn-bundle 14 passes through at least one more guide 46 centered on the axis of rotation of and above rotating feed-device I8.

Deknitting of heat-set tubing 50 prepared using two individual ends of yarn is shown in FIGS. 3 and 4. Tubing 50 is collected during knitting without permitting it to twist about its longitudinal axis, and it is fed to deknitting without introducing any such twist, i.e., maintained in a twistless state. It cannot be allowed to fall at random on the floor or to unwind from a stationary roll of tubing 50 because these operations introduce real twist which leads to eventual yarn-breaks. A preferred method for collecting and feeding tubing 50 is to cause it to pleat upon itself in progressive layers by backward and forward alternating folds, as indicated in FIGS. 4 and 6. This is most readily effected by collecting it in a tall box (not shown) of the proper width to just accommodate the full width of heat-set tubing 50. As shown, the yarn-bundle 52 and separated individual textured yarns 70 are drawn through the deknitting operation by the windup devices 60. Unraveling of heat-set yarn-bundle 52 from one end of the tubing 50 occurs readily as bundle 52 is pulled upward. The unraveling point is not indicated in FIG. 4 (or FIG. 6). While it tends to vary somewhat, it always remains close to the pile of tubing 50.

Bundle 52 is led upwardly to and partly around freely rotatable pulley 54. A relatively long upward path of the bundle 52 is preferred because it helps to disentangle the now intimately associated, individual, textured yarn-ends 70. Use of freely rotatable pulley 54 prevents the backing up of any residual false twist. Next, yarnbundle 52 progresses to the separation-guide (or eye) 56 beyond which individual heat-set yarn-ends 70 are conveyed along angularly separated paths. Angular separation of yarn-ends 70 at this point forces the relief of any false twist remaining in bundle 52. Additional guides 58 lead textured yarns 70 to windup on separate winding devices 60.

It is essential that the linear rate of movement of yarn-ends 70, calculated on the basis of straightened yarn-length, be essentially identical for each. Otherwise, slack may develop in one or more ends, which eventually leads to snarling and breaking. Particularly when operating with only two yarn-ends 70, it ordinarily suffices to operate all windups 60 at identical peripheral velocities. The provision of a tensioning device 62 for each yarn-end 70 (FIG. 4) is sometimes desirable for promoting equality of linear rates. Alternatively, or additionally, each yarn 70 may run over freely rotatable fixed rolls 63 down to and around a vertically displaceable freely rotatable roll 64, the vertical displacement of which may be used to generate electric signals which, in turn, can correct the rotational speeds of windups 60 (FIG. 8).

FIGS. 5 and 6 show deknitting of four ends of textured yarn 70. This is substantially as just described for two ends. As the number of yarn-ends 70 in bundle 52 increases, there is a corresponding reduction of yarntension per end which results in a tendency for the ends to resist separation. Particularly when more than two individual yarn-ends 70 are involved, passage of bundle 52 through a tensioning device 66 located between pulley 54 and separation-guide 56 promotes disassociation of the ends before physical separation. Improved separation is also promoted if the opening in separation-guide 56 is relatively large, e.g., 0.5-1.0 inch.

FIG. 7 shows schematically, with elements numbered consistently with the preceding Figures, a preferred process of the present invention wherein the knitting and deknitting operations are directly coupled. Thus, as heat-set tubing 50 passes beyond forwarding rolls 28, the bundle 52 is continuously deknitted at 72 and led over pulley 54, to separation-guide 56, and thence as individual yarn-ends to windups 60. In such a coupled process, it is essential either that the knitting and deknitting operations be perfectly matched or that, at least, there always be some tubing 50 extending beyond rolls 28 before unraveling point 72.

A key requirement of successful knit-deknit processing using plural ends of yarn is that no real twist be inserted at any point. Use of a stationary creel and a stationary circular-knitting needle-bed assures the absence of real twist during knitting. Prevention of any of of the knit-tubing before and during deknitting assures the continued absence of inserted real twist. Any real twist in the feed-yarns 10 as they leave their packages 12 on creel 42 is, of course, of no consequence.

Because circular knitting without some rotation is impossible, it is unavoidable that some false twist be generated by rotating feed-device 18. It is essential that the process be operated so as to minimize any accumulation of false twist and to provide for the relaxation of any false twist introduced prior to separation of heat set yarn-ends 70. To this end, the length of yarn-travel from convergence-guide 44 (FIGS. 1, 2 and 7) to feedopening 20 in rotating feed-device 18 is preferably minimized. Convergence-guide 44 acts to some extent as a barrier to false twist. By arranging for each feedyarn 10 to approach convergence-guide 44 a a different angle, false twist is forcibly released by slippage at convergence-guide 44. Most, but not necessarily all, of the generated false twist is relieved in this fashion.

It is essential in the remainder of the process, i.e., deknitting, that residual false twist and any additional false twist introduced by the knitting operation be relieved. In order to avoid the accumulation of false twist between unraveling point 72 and the first downstream guide thereafter, the surfaces of this first downstream guide should move with bundle 52, for example, freely rotatable pulley 54. Final release of all residual false twist is assured by leading the textured yarn-ends 70 from separation-guide 56 along paths angularly separated from one another and by providing sufficiently distance between pulley 54 and separationguide 56 for the complete relief of false twist. This distance should be at least 2 feet for reliably continuous operation.

Finally, it is required that each individual textured yarn 70 be wound up at the same average linear rate based on straightened yarn-length. Otherwise, slack accumulates in one or more yarn-ends leading eventually to snarling and yarn-breaks. All individual yarns 10 are led to knitting head 16 at identical linear rates. This is ordinarily assured by the friction from multiple guides 30 in the path of each yarn 10. It is preferred, however, to use a positive-feed yarn-metering device such as device 32 of FIG. 2. Likewise, it is ordinarily effective in the winding of textured yarns 70 to obtain equal linear rates by operating the plurality of windups 60 at identical speeds. Because of the effects of texturing, it is possible that operating all windups 60 at identical speeds can introduce minor variations in linear rates of yarn-windup. The random accumulation of such variations in the path of one end results in generation of slack. It is preferred, therefore, to control the speed of the windups 60 such that all textured yarns 70 are wound at identical linear rates regardless of minor variations resulting from texturing.

Numerous modifications to the specific embodiments described herein may be made without departing from the scope of this invention. Heat-setting need not be directly coupled with knitting but may occur, as is well know, in an entirely separate step, e.g., in an autoclave. The plurality of feed-yarns converged for knitting need not be identical. Novel texturing effects result, for example, if the yarns differ in denier, in heat shrinkage, or in both of these properties.

The utility of knit-deknit textured yarns is well established. Their use in sheer knit stocking is well known. A particularly effective use of these yarns involves beaming them and using the beam of textured yarns as the backbar in crepe fabrics.

EXAMPLE I Two ZO-denier monofilaments of normally drawn nylon'66 textile yarn are knit-deknit textured substantially as shown by the combination of FIGS. 1, 3 and 4. The knitting device is a circular-knitting machine with both stationary creel and stationary circular needlebed. Feed-rate of each yarn to the knitting head is 683 yd./min. The heat-setting plates are maintained at surface-temperatures of 350F. The heat-set knit tubing is collected by folding it carefully back and forth upon itself without permitting any twist.

In deknitting, the knit tubing is gradually unfolded, again without permitting any twist of the tubing. Pulley 54 is about 6.5 feet above the tubing. A space of about 5 feet is provided between pulley 54 and separationguide 56. Guides 58 first downstream of separationguide 56 are about 2 feet apart and each 3 feet from separation-guide 56. Identical gate-tension guides 62 are employed. The two windups 60 are positions on a Kidde-Sipp spooler positively driven at identical peripheral velocities of 240 yd./min.Deknitting is continuous and trouble-free when the yarn-bundle is fed from either end of the knit tubing. Comparison of the two textured ends shows the two to be equivalently textured with extremely uniform saw-tooth-like crimp.

The latter is characterized by relatively long straight portions of yarn in zigzag arrangement with relatively short sharply rounded apices.

EXAMPLE II Example .I is repeated in every detail except that a positive-feed yarn-metering device as described in connection with FIG. 2 is employed. Equivalent operation and results are obtained.

EXAMPLE III Example II is repeated with the substitution of 70-denier 34-filament normally drawn nylon-66 textile yarn. The windup rate for the textured yarn is about 500 yd/min. Size, shape and dimensions of the uniform saw-tooth-like crimp are substantially the same as obtained in Examples I and II.

EXAMPLE lV Three ends of ZO-denier nylon-66 normally drawn textile monofilament are knitted into tubing as shown in FIG. 2. Feed-rate of each yarn is about 600 yd./min. Heat-setting is accomplished using a heater temperature of 350 F. The heat-set tubing is collected and transported in the pleated fashion described so as to prevent the insertion of any real twist.

Deknitting is accomplished essentially as shown in FIGS. 5 and 6 with the exception that three rather than four ends are involved and that, after passing separately through guides 58, the textured ends are reconverged for windup together on a single roll 60. This latter step accomplishes the same effect as winding onthree rolls 60 all operated at identical speeds. Windup is at about 500 yd./min./end.

When this three-end knit-deknit process is carried out without a tensioning device 66, some difficulty results at separation-guide 56 because some yarn-loops fail to disengage from one another, due to the low yarntension per individual end. This problem is obviated by passing yarn-bundle 52 through a Stehedco UTC Tension Device at the number 3 setting. Pulley 54 is about 6.5 feet above the pleated supply of tubing 50; yarntension device 66 is about 3 feet from pulley 54; separation-guide 56, with inside diameter of about 1 inch, is about 8 feet from yarn-tens'ioner 66 to provide plenty of distance for complete relief of false twist; guides 58 are positioned about 3 feet from separationguide 56 and spaced to provide about 25 degrees separation between adjacent yarn-paths; and the individual ends are reconverged at the windup 60 about 2 feet from guides 58.

The uniform zigzag crimp obtained is very similar to that of Examples I-III, but the apices between relatively shorter straight sections are more broadly rounded.

EXAMPLE V Example IV is essentially duplicated except for utilizing four ZO-denier monofilaments rather than three and for utilizing the number 4 setting of the Stehedco UTC Tension Device. In deknitting, the four ends are pulled form separation guide 56 along; paths separated by about 25 (as shown in FIG. 5) and are then reconverged for winding on a single roll. 60. The four ends exhibit uniform regular crimp similar to that of the previ-v ous examples, the apices being sharper than those for Example IV.

It is apparent that the number of individual yarns which can be processed simultaneously according to the present knit-deknit invention is limited only by the size, design and spacing of needles in the knitting head employed.

What is claimed is:

1. In a process for texturing yarn that includes the steps of knitting a single end of yarn into a tube without the introduction of real twist via a circular knitting machine having a cylindrical needle bed and a feed device for applying yarn to the needles, heat-setting the knit tube, unraveling said yarn from said tube and winding the unraveled yarn into a package, the improvement comprising: feeding a plurality of yarn ends at substantially equal linear speeds from sources along separate paths, said sources and said cylinder maintaintwist; unraveling said bundle from said tube while maintaining said tube in a twistless state; separating said bundle into yarn ends and taking up each end at about the same linear speed.

2. The process of claim 1, wherein said needle bed and yarn sources are stationary.

3. The process as defined in claim 1, said process being continuous. 

1. In a process for texturing yarn that includes the steps of knitting a single end of yarn into a tube without the introduction of real twist via a circular knitting machine having a cylindrical needle bed and a feed device for applying yarn to the needles, heat-setting the knit tube, unraveling said yarn from said tube and winding the unraveled yarn into a package, the improvement comprising: feeding a plurality of yarn ends at substantially equal linear speeds from sources along separate paths, said sources and said cylinder maintaining the same relative position with respect to each other; converging said yarn ends along differently angled paths with respect to each other into a bundle in a guide receiving same, said guide being in close proximity to the feed device, relative movement occurring between the feed device on the one hand and the cylindrical needle bed and the yarn sources on the other hand; knitting the bundle into a tube without the introduction of real twist or substantial buildup of false twist; unraveling said bundle from said tube while maintaining said tube in a twistless state; separating said bundle into yarn ends and taking up each end at about the same linear speed.
 2. The process of claim 1, wherein said needle bed and yarn sources are stationary.
 3. The process as defined in claim 1, said process being continuous. 